1. Field of the Invention
The invention relates to a heating and/or air-conditioning apparatus particularly for the cabin of a motor vehicle.
2. Discussion of the Related Art
In motor vehicle heating and/or air-conditioning units of the prior art, it is known practice to use an air blowing member, typically a blower, placed upstream of a heating system, typically made up of an evaporator/radiator, allowing the air expelled by the blower to be heated up by heat exchange. In general, a liquid such as water flows around inside the radiator under the control of a progressive valve. These members are placed in succession in a chassis inside which the air flows towards one or more ducts that convey air into the cabin.
In addition, a fresh air passage is conventionally formed on the wall of the chassis, outside of the radiator, and a hinged mixing shutter is provided to partially or fully open or close this passage so as to transmit fresh air towards the ducts, or not as the case may be.
Control of the temperature of the air conveyed to the ducts is managed by a central unit which controls the valve and the shutter operating in concert. Thus, in a first state, when only hot air is required, the valve is in a wide open operating position and the shutter is closed. All of the air therefore passes through the radiator. When warm air is required, in a variable operating state, the shutter is partially opened and the radiator valve governs the temperature of the water circuit so as to provide warm air which mixes with the fresh air. The progressive nature in raising or lowering the temperature is assisted by the valve. Finally, when only cold air is required in a second extreme state, the valve shuts off the water circuit and the fresh air passage shutter is wide open.
This solution is not satisfactory, particularly for economical reasons, because of the high cost of the progressive valve and the significant pressure drops in the liquid which are created by the valve when it is open.
The object of the invention is to allow good control over the progressive nature of the temperature for an appreciably lower cost.
To do that, provision is made for the complex valve to be replaced by a simple valve, coupled to means of mixing the air from the fresh air passage and from the radiator.
More specifically, the subject of the invention is heating and/or air-conditioning apparatus particularly for the cabin of a motor vehicle, having: a chassis within which air flows, this chassis being equipped with an air-blowing means and with a means for cooling and heating the air, which operates using a fluid flowing through it, a member for controlling the heating means, at least one air flow duct communicating with the chassis, and at least one mixing shutter with a variable degree of openness for allowing the air stream towards the duct.
In this apparatus, the member controlling the heating means is of the on/off type and the mixing shutter is arranged, in the overall direction of air flow, downstream of the heating member, particularly facing a heating surface of the heating means.
Advantageously, in an intermediate position of the air flow through the heating means being shut off, the mixing shutter governs the switching of the member controlling the heating means between the on and off modes.
According to a first particular embodiment, the fresh air passage is defined between a wall of the chassis and a side wall of the heating means. The arrangement having the following characteristics:
two operating states are considered, a first state in which the heating means (valve open) is on and the mixing shutter opens the fresh air passage to the intermediate position, and a second state in which the heating is off and the shutter pivots beyond the intermediate position to allow additional fresh air to pass through the switched-off heating means (valve closed);
when the shutter is in a first extreme position, the control member is in the on position and the shutter closes off the fresh air passage so that the air blown passes only through the heating means to form a hot air stream directed towards the duct;
between the first position and the intermediate position of the shutter in the first state, the control member remains in the on position and the shutter allows a variable fresh air stream to pass through the passage according to the orientation of the shutter, and also lets through a hot air stream from the heating means so that these streams mix as they head for the duct;
when the shutter reaches the intermediate position, the control member switches to the off position and the shutter prevents air from the heating means from flowing so that the air blown passes only through the fresh air passage; and
between the intermediate position and a second extreme position of the shutter in the second state, and in this second position, the control member remains in the off position and the shutter is directed toward the heating means so that additional fresh air passes through the heating means, now off, bound for the duct and adds to the fresh air stream coming from the passage.
According to an alternative form of the embodiment:
aside from the mixing shutter, the apparatus comprises an additional shutter also arranged downstream of the heating means, so that the two shutters are capable, in a given position, of closing off the flow of air passing through the heating means, and:
between a first position and before reaching a second position of the mixing shutter, the first state is defined by the mixing shutter switching from the fresh air passage being closed so that the blown air passes only through the heating means to form a hot air stream bound for the duct, to variable opening of the fresh air passage then in collaboration with the additional shutter so as to allow a hot air stream from the heating means to pass so that these streams mix as they head for the duct;
when the mixing shutter reaches the second position, the control member switches to the off position and the additional shutter being arranged in a first closed position, the shutters then collaborate to shut off the flow of air from the heating means so that the air blown passes only through the fresh air passage; and
between this first and a second position of the additional shutter, the mixing shutter remaining in its second position and the control member in the off position, the second state is defined by an opening of the air passage through the heating means, now off, which provides additional fresh air bound for the duct and adds to the fresh air stream coming from the fresh air passage.
According to another embodiment, a fresh air passage is provided between a wall of the chassis and a side wall of the heating means. The arrangement having the following characteristics:
the mixing shutter controls the shutting-off of the air flow through the heating means in a closed position, this flow passage being opened variably outside of this position;
the apparatus further comprises an additional shutter arranged in the chassis in such a way as to close off the fresh air passage in a closed position and to open this passage variably outside of this position;
the mixing shutter being in the closed position and the additional shutter in the open position, the control member of the heating means is in the off mode and the air blown passes only through the fresh air passage;
the mixing and additional shutters being outside of the closed positions, the control member of the heating means is in the on mode and the additional shutter allows a fresh air stream to pass through the passage and the mixing shutter allows a hot air stream from the heating means to pass so that these streams mix as they head for the duct;
the mixing shutter being outside of the closed position and the additional shutter in the closed position, the control member is in the on mode so that the blown air passes only through the heating means so as to form a hot air stream bound for the duct; and
when the shutters are in the open position, the control member is in the off mode so that additional fresh air passes through the heating means, now off, bound for the duct and adds to the fresh air stream coming from the passage.
Another subject of the invention is a vehicle equipped with heating and/or air-conditioning apparatus as described previously.